The invention relates to a system for testing solid-liquid two-phase flowing with an adjustable inclined pipe angle, and belongs to the technical field of two-phase flowing experiment tests. Accordingto the system, a closed solid-liquid two-phase flowing circulation loop is formed by a fixed pipeline, a dredge pump, an inlet flexible elbow, a transparent glass pipe, an inclined test pipeline, anoutlet flexible elbow, a rigid elbow, a flexible pipeline, a steering flexible elbow and a horizontal extending pipe, wherein a solid particle dosing system is arranged above the fixed pipeline, a supporting platform is arranged under the horizontal extending pipe; a lifting hydraulic cylinder is arranged under the supporting platform to support platform lifting adjustment. The system has functions of testing hydraulic loss and pressure change of solid-liquid two-phase flowing in pipelines having different inclined angles and observing solid-liquid two-phase flowing form in pipelines having different inclined angles and the like, a platform for studying the solid-liquid two-phase flowing mechanism can be provided, and the system can be applied to deep studying of hydraulic characteristicsand internal status of solid-liquid two-phase flowing.